Grammatical elements include function words, which are those words that do not have semantic meaning in a text fragment. An example of such function words are Japanese case markers, which indicate grammatical relations (such as subject, object, and location) of the complement noun phrase to the predicate. Other grammatical elements include inflections, such as inflections to indicate number, tense, gender, etc. For instance, the ending of the word “come” changes based on the number of the noun associated with it (i.e., I come, she comes).
Generation of grammatical elements using natural language processing technology has become important. This is particularly true in the context of machine translation. In an English-to-Japanese machine translation system, for example, Japanese case markers are among the most difficult to generate appropriately. This is because the case markers often do not correspond to any word in the source language (in English), since many grammatical relations are expressed by word order in English.
Generating Japanese case markers is also difficult because the mapping between the case markers and the grammatical relations they express is very complex. For the same reasons, generation of case markers is challenging to foreign language learners.
This difficulty in generation, however, does not mean that the choice of case markers is insignificant. When a generated sentence contains mistakes in grammatical elements, those mistakes often lead to severe unintelligibility, which sometimes results in a different semantic interpretation from the intended one. The same is true not only of case markers, but of substantially all grammatical elements.
An example is helpful in showing how difficult it is to reliably predict grammatical elements. The example is in predicting case markers in Japanese using the information that exists only in the rest of the sentence.
The following is an example of a Japanese translation of the phrase “(He) has idolized Einstein since (he was) little.” The first line shows the Japanese characters, the second line shows the characters phonetically spelled using the English alphabet, and the third line shows the English translation of the characters. The sentence contains two case markers, “kara” which means “from” and “ni” which does not correspond to any word in English.
      Chisai  toki kara  ainshutain  ni  akogareru  itasmall  time from  Einstein  NI idolize PROG.PAST“(he) has idolized Einstein since (he was) little”In the example, square brackets indicate phrase, or “bunsetsu” boundaries, and arrows between phrases indicate dependency relations.
In order to predict the case markers in this sentence, there are multiple valid answers for each decision, many of which correspond to different semantic relations. For example, for the first case marker slot in the example, which is currently filled by “kara”, other grammatical elements “wa” (which is a topic marker) and “ni” which means “in”, or no case marker at all, are all reasonable choices. Other markers, such as “wo” (which is an object marker), “de” which means “at”, or “made” which means “until”, etc., are not considered reasonable.
For the second grammatical case marker slot filled by “ni”, other case markers such as “ga” (which is a subject marker) are also grammatically reasonable choices, making “Einstein” the subject of “idolize”, thus changing the meaning of the sentence.
As is apparent from this example, the choice among the correct answers is determined by the speaker's intent in uttering the sentence, and is therefore very difficult to recover from the content words of the sentence structure alone.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.